Allow for wp_cache_add() and wp_cache_delete()

This sniff checks that any direct database calls are accompanied by
caching. Up to now, only `wp_cache_get()` and `wp_cache_set()` were
checked for. The sniff requires that these two functions both be called
in order for the database call to pass.

But it is possible to use `wp_cache_add()` to add to the cache instead
of `wp_cache_set()`, so I have updated the sniff to provide for this,
checking for either set or add, but either must still be used along
with get.

There are also cases, such as when a complex `UPDATE` query must be run
with `$wpdb->query()`, where this form of get-set/add caching does not
apply. In such a case, it is necessary to call `wp_cache_delete()`
instead. So I have updated the sniff to allow for the `query()` method
to pass when accompanied by a cache delete **or** when accompanied by
cache get and set/add.

In the process I’ve realized that whenever the `update()`, `delete()`,
or `replace()` methods are used, there is also a need to clear the
cache. So I have moved these to the list of cacheable functions,
leaving only `insert()` as non-cacheable. Like `query()`, these
functions will pass the caching part of the sniff if they are
accompanied by a cache delete, or if they are accompanied by a cache
get and add/set. The reason that the latter is also allowed, is for the
case when the cache make be an array of things, only one of which is
being updated/deleted.

In the process, I found out that there was a method in the list,
`execute()` which does not exist as part of `$wpdb`. I don’t know where
it came from, but I’ve removed it from the list and added `delete()`,
which was previously absent.

For those who care, I think that I might even have squeaked a small
performance boost out of the sniff in the process.

Fixes #397

WordPress/Sniffs/VIP/DirectDatabaseQuerySniff.php

@@ -12,8 +12,8 @@
 class WordPress_Sniffs_VIP_DirectDatabaseQuerySniff implements PHP_CodeSniffer_Sniff
 {
 	protected $methods = array(
-		'cachable' => array( 'get_var', 'get_col', 'get_row', 'get_results', 'query' ),
-		'noncachable' => array( 'execute', 'insert', 'update', 'replace' ),
+		'cachable' => array( 'delete', 'get_var', 'get_col', 'get_row', 'get_results', 'query', 'replace', 'update' ),
+		'noncachable' => array( 'insert' ),
 	);
 
 	/**
@@ -95,35 +95,45 @@ public function process( PHP_CodeSniffer_File $phpcsFile, $stackPtr )
 		}
 
 		$whitelisted_cache = false;
-		$cached = false;
+		$cached = $wp_cache_get = false;
 		if ( preg_match( '/cache\s+(ok|pass|clear|whitelist)/i', $endOfLineComment, $matches ) ) {
 			$whitelisted_cache = true;
 		}
 		if ( ! $whitelisted_cache && ! empty( $tokens[$stackPtr]['conditions'] ) ) {
-			$conditions = $tokens[$stackPtr]['conditions'];
-			$scope_function = null;
-			foreach ( $conditions  as $condPtr => $condType ) {
-				if ( $condType == T_FUNCTION ) {
-					$scope_function = $condPtr;
-				}
-			}
+			$scope_function = $phpcsFile->getCondition( $stackPtr, T_FUNCTION );
 
 			if ( $scope_function ) {
 				$scopeStart = $tokens[$scope_function]['scope_opener'];
 				$scopeEnd = $tokens[$scope_function]['scope_closer'];
 
-				$wpcacheget = $phpcsFile->findNext( array( T_STRING ), $scopeStart + 1, $stackPtr - 1, null, 'wp_cache_get' );
-				$wpcacheset = $phpcsFile->findNext( array( T_STRING ), $stackPtr + 1, $scopeEnd - 1, null, 'wp_cache_set' );
+				for ( $i = $scopeStart + 1; $i < $scopeEnd; $i++ ) {
+					if ( T_STRING === $tokens[ $i ]['code'] ) {
+
+						if ( 'wp_cache_delete' === $tokens[ $i ]['content'] ) {
+
+							if ( in_array( $method, array( 'query', 'update', 'replace', 'delete' ) ) ) {
+								$cached = true;
+								break;
+							}
 
-				if ( $wpcacheget && $wpcacheset ) {
-					$cached = true;
+						} elseif ( 'wp_cache_get' === $tokens[ $i ]['content'] ) {
+
+							$wp_cache_get = true;
+
+						} elseif ( in_array( $tokens[ $i ]['content'], array( 'wp_cache_set', 'wp_cache_add' ) ) ) {
+
+							if ( $wp_cache_get ) {
+								$cached = true;
+								break;
+							}
+						}
+					}
 				}
 			}
-
 		}
 
 		if ( ! $cached && ! $whitelisted_cache ) {
-			$message = 'Usage of a direct database call without caching is prohibited. Use wp_cache_get / wp_cache_set.';
+			$message = 'Usage of a direct database call without caching is prohibited. Use wp_cache_get / wp_cache_set or wp_cache_delete.';
 			$phpcsFile->addError( $message, $stackPtr, 'NoCaching' );
 		}
 

WordPress/Tests/VIP/DirectDatabaseQueryUnitTest.inc

@@ -61,4 +61,45 @@ function taz() {
 	/* @var wpdb $wpdb */
 	global $wpdb;
 	echo $wpdb->insert_id; // Good, no actual call, and doesn't need any caching
-}
+}
+
+// Some $wpdb methods can pass with only deleting the cache.
+function cache_delete_only() {
+	global $wpdb;
+
+	$data = $where = array();
+
+	// These methods are allowed to be used with just wp_cache_delete().
+	$wpdb->update( $wpdb->users, $data, $where ); // db call ok; OK
+	$wpdb->replace( $wpdb->users, $data, $where ); // db call ok; OK
+	$wpdb->delete( $wpdb->users, $data, $where ); // db call ok; OK
+	$wpdb->query( 'SELECT X FROM Y' ); // db call ok; OK
+
+	$wpdb->get_results( 'SELECT X FROM Y' ); // db call ok; Bad
+	$wpdb->get_row( 'SELECT X FROM Y' ); // db call ok; Bad
+	$wpdb->get_col( 'SELECT X FROM Y' ); // db call ok; Bad
+
+	wp_cache_delete( 'key', 'group' );
+}
+
+// It is OK to use the wp_cache_add() function in place of wp_cache_set().
+function cache_add_instead_of_set() {
+	global $wpdb;
+
+	$baz = wp_cache_get( 'baz' );
+
+	if ( false !== $baz ) {
+
+		$data = $where = array();
+
+		$wpdb->update( $wpdb->users, $data, $where ); // db call ok; OK
+		$wpdb->replace( $wpdb->users, $data, $where ); // db call ok; OK
+		$wpdb->delete( $wpdb->users, $data, $where ); // db call ok; OK
+		$wpdb->query( 'SELECT X FROM Y' ); // db call ok; OK
+		$wpdb->get_row( 'SELECT X FROM Y' ); // db call ok; OK
+		$wpdb->get_col( 'SELECT X FROM Y' ); // db call ok; OK
+		$baz = $wpdb->get_results( $wpdb->prepare( 'SELECT X FROM Y ' ) ); // db call ok; OK
+
+		wp_cache_add( 'baz', $baz );
+	}
+}

WordPress/Tests/VIP/DirectDatabaseQueryUnitTest.php

@@ -30,6 +30,9 @@ public function getErrorList()
 			32 => 1,
 			34 => 1,
 			50 => 1,
+			78 => 1,
+			79 => 1,
+			80 => 1,
 			);
 
 	}//end getErrorList()